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Subject[GIT pull] timers core for 2.6.33
Linus,

Please pull the latest timers-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git timers-for-linus

Thanks,

tglx

------------------>
H Hartley Sweeten (1):
clockevents: Add missing include to pacify sparse

John Stultz (2):
time: Implement logarithmic time accumulation
time: Remove xtime_cache

Jon Hunter (2):
nohz: Prevent clocksource wrapping during idle
nohz: Allow 32-bit machines to sleep for more than 2.15 seconds

Martin Schwidefsky (2):
nohz: Reuse ktime in sub-functions of tick_check_idle.
nohz: Introduce arch_needs_cpu

Mike Travis (1):
timers, init: Limit the number of per cpu calibration bootup messages

Stanislaw Gruszka (1):
posix-cpu-timers: optimize and document timer_create callback

Stephen Rothwell (1):
sparc: fix printk for change of variable type

Thomas Gleixner (8):
clockevents: Use u32 for mult and shift factors
clocksource: Provide a generic mult/shift factor calculation
mips: Use generic mult/shift factor calculation for clocks
nohz: Type cast printk argument
nohz: Track last do_timer() cpu
clocksource/events: Fix fallout of generic code changes
x86: Fix printk format due to variable type change
x86: vmiclock: Fix printk format


arch/mips/include/asm/time.h | 14 +++-
arch/mips/kernel/time.c | 33 ---------
arch/powerpc/kernel/time.c | 2 +-
arch/s390/include/asm/cputime.h | 8 ++
arch/s390/kernel/s390_ext.c | 2 +
arch/s390/kernel/vtime.c | 2 +
arch/sparc/kernel/time_64.c | 2 +-
arch/x86/kernel/apic/apic.c | 2 +-
arch/x86/kernel/vmiclock_32.c | 2 +-
drivers/s390/cio/cio.c | 1 +
include/linux/clockchips.h | 19 ++++--
include/linux/clocksource.h | 12 +++
include/linux/tick.h | 5 ++
include/linux/time.h | 1 +
include/linux/timex.h | 4 -
init/calibrate.c | 24 ++++---
kernel/cpu.c | 5 +-
kernel/hrtimer.c | 3 +-
kernel/posix-cpu-timers.c | 5 +-
kernel/time.c | 1 -
kernel/time/clockevents.c | 13 ++--
kernel/time/clocksource.c | 97 +++++++++++++++++++++++++++
kernel/time/tick-oneshot.c | 4 +-
kernel/time/tick-sched.c | 141 ++++++++++++++++++++++++---------------
kernel/time/timekeeping.c | 119 ++++++++++++++++++++-------------
kernel/time/timer_list.c | 10 ++-
26 files changed, 353 insertions(+), 178 deletions(-)

diff --git a/arch/mips/include/asm/time.h b/arch/mips/include/asm/time.h
index df6a430..c7f1bfe 100644
--- a/arch/mips/include/asm/time.h
+++ b/arch/mips/include/asm/time.h
@@ -84,8 +84,16 @@ static inline int init_mips_clocksource(void)
#endif
}

-extern void clocksource_set_clock(struct clocksource *cs, unsigned int clock);
-extern void clockevent_set_clock(struct clock_event_device *cd,
- unsigned int clock);
+static inline void clocksource_set_clock(struct clocksource *cs,
+ unsigned int clock)
+{
+ clocksource_calc_mult_shift(cs, clock, 4);
+}
+
+static inline void clockevent_set_clock(struct clock_event_device *cd,
+ unsigned int clock)
+{
+ clockevents_calc_mult_shift(cd, clock, 4);
+}

#endif /* _ASM_TIME_H */
diff --git a/arch/mips/kernel/time.c b/arch/mips/kernel/time.c
index 1f467d5..fb74974 100644
--- a/arch/mips/kernel/time.c
+++ b/arch/mips/kernel/time.c
@@ -71,39 +71,6 @@ EXPORT_SYMBOL(perf_irq);

unsigned int mips_hpt_frequency;

-void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock)
-{
- u64 temp;
- u32 shift;
-
- /* Find a shift value */
- for (shift = 32; shift > 0; shift--) {
- temp = (u64) NSEC_PER_SEC << shift;
- do_div(temp, clock);
- if ((temp >> 32) == 0)
- break;
- }
- cs->shift = shift;
- cs->mult = (u32) temp;
-}
-
-void __cpuinit clockevent_set_clock(struct clock_event_device *cd,
- unsigned int clock)
-{
- u64 temp;
- u32 shift;
-
- /* Find a shift value */
- for (shift = 32; shift > 0; shift--) {
- temp = (u64) clock << shift;
- do_div(temp, NSEC_PER_SEC);
- if ((temp >> 32) == 0)
- break;
- }
- cd->shift = shift;
- cd->mult = (u32) temp;
-}
-
/*
* This function exists in order to cause an error due to a duplicate
* definition if platform code should have its own implementation. The hook
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 92dc844..60ceb27 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -905,7 +905,7 @@ static void register_decrementer_clockevent(int cpu)
*dec = decrementer_clockevent;
dec->cpumask = cpumask_of(cpu);

- printk(KERN_DEBUG "clockevent: %s mult[%lx] shift[%d] cpu[%d]\n",
+ printk(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
dec->name, dec->mult, dec->shift, cpu);

clockevents_register_device(dec);
diff --git a/arch/s390/include/asm/cputime.h b/arch/s390/include/asm/cputime.h
index 24b1244..95f3561 100644
--- a/arch/s390/include/asm/cputime.h
+++ b/arch/s390/include/asm/cputime.h
@@ -183,6 +183,7 @@ struct s390_idle_data {
unsigned long long idle_count;
unsigned long long idle_enter;
unsigned long long idle_time;
+ int nohz_delay;
};

DECLARE_PER_CPU(struct s390_idle_data, s390_idle);
@@ -198,4 +199,11 @@ static inline void s390_idle_check(void)
vtime_start_cpu();
}

+static inline int s390_nohz_delay(int cpu)
+{
+ return per_cpu(s390_idle, cpu).nohz_delay != 0;
+}
+
+#define arch_needs_cpu(cpu) s390_nohz_delay(cpu)
+
#endif /* _S390_CPUTIME_H */
diff --git a/arch/s390/kernel/s390_ext.c b/arch/s390/kernel/s390_ext.c
index 0de305b..59618bc 100644
--- a/arch/s390/kernel/s390_ext.c
+++ b/arch/s390/kernel/s390_ext.c
@@ -126,6 +126,8 @@ void __irq_entry do_extint(struct pt_regs *regs, unsigned short code)
/* Serve timer interrupts first. */
clock_comparator_work();
kstat_cpu(smp_processor_id()).irqs[EXTERNAL_INTERRUPT]++;
+ if (code != 0x1004)
+ __get_cpu_var(s390_idle).nohz_delay = 1;
index = ext_hash(code);
for (p = ext_int_hash[index]; p; p = p->next) {
if (likely(p->code == code))
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index c41bb0d..b59a812 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -167,6 +167,8 @@ void vtime_stop_cpu(void)
/* Wait for external, I/O or machine check interrupt. */
psw.mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_IO | PSW_MASK_EXT;

+ idle->nohz_delay = 0;
+
/* Check if the CPU timer needs to be reprogrammed. */
if (vq->do_spt) {
__u64 vmax = VTIMER_MAX_SLICE;
diff --git a/arch/sparc/kernel/time_64.c b/arch/sparc/kernel/time_64.c
index da1218e..63f73ae 100644
--- a/arch/sparc/kernel/time_64.c
+++ b/arch/sparc/kernel/time_64.c
@@ -847,7 +847,7 @@ void __init time_init(void)
sparc64_clockevent.min_delta_ns =
clockevent_delta2ns(0xF, &sparc64_clockevent);

- printk("clockevent: mult[%lx] shift[%d]\n",
+ printk("clockevent: mult[%ux] shift[%d]\n",
sparc64_clockevent.mult, sparc64_clockevent.shift);

setup_sparc64_timer();
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 894aa97..cf4ee51 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -662,7 +662,7 @@ static int __init calibrate_APIC_clock(void)
calibration_result = (delta * APIC_DIVISOR) / LAPIC_CAL_LOOPS;

apic_printk(APIC_VERBOSE, "..... delta %ld\n", delta);
- apic_printk(APIC_VERBOSE, "..... mult: %ld\n", lapic_clockevent.mult);
+ apic_printk(APIC_VERBOSE, "..... mult: %u\n", lapic_clockevent.mult);
apic_printk(APIC_VERBOSE, "..... calibration result: %u\n",
calibration_result);

diff --git a/arch/x86/kernel/vmiclock_32.c b/arch/x86/kernel/vmiclock_32.c
index 611b9e2..74c92bb 100644
--- a/arch/x86/kernel/vmiclock_32.c
+++ b/arch/x86/kernel/vmiclock_32.c
@@ -226,7 +226,7 @@ static void __devinit vmi_time_init_clockevent(void)
evt->min_delta_ns = clockevent_delta2ns(1, evt);
evt->cpumask = cpumask_of(cpu);

- printk(KERN_WARNING "vmi: registering clock event %s. mult=%lu shift=%u\n",
+ printk(KERN_WARNING "vmi: registering clock event %s. mult=%u shift=%u\n",
evt->name, evt->mult, evt->shift);
clockevents_register_device(evt);
}
diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 138124f..126f240 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -618,6 +618,7 @@ void __irq_entry do_IRQ(struct pt_regs *regs)
old_regs = set_irq_regs(regs);
s390_idle_check();
irq_enter();
+ __get_cpu_var(s390_idle).nohz_delay = 1;
if (S390_lowcore.int_clock >= S390_lowcore.clock_comparator)
/* Serve timer interrupts first. */
clock_comparator_work();
diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
index 3a1dbba..0cf725b 100644
--- a/include/linux/clockchips.h
+++ b/include/linux/clockchips.h
@@ -77,10 +77,10 @@ enum clock_event_nofitiers {
struct clock_event_device {
const char *name;
unsigned int features;
- unsigned long max_delta_ns;
- unsigned long min_delta_ns;
- unsigned long mult;
- int shift;
+ u64 max_delta_ns;
+ u64 min_delta_ns;
+ u32 mult;
+ u32 shift;
int rating;
int irq;
const struct cpumask *cpumask;
@@ -116,8 +116,8 @@ static inline unsigned long div_sc(unsigned long ticks, unsigned long nsec,
}

/* Clock event layer functions */
-extern unsigned long clockevent_delta2ns(unsigned long latch,
- struct clock_event_device *evt);
+extern u64 clockevent_delta2ns(unsigned long latch,
+ struct clock_event_device *evt);
extern void clockevents_register_device(struct clock_event_device *dev);

extern void clockevents_exchange_device(struct clock_event_device *old,
@@ -130,6 +130,13 @@ extern int clockevents_program_event(struct clock_event_device *dev,

extern void clockevents_handle_noop(struct clock_event_device *dev);

+static inline void
+clockevents_calc_mult_shift(struct clock_event_device *ce, u32 freq, u32 minsec)
+{
+ return clocks_calc_mult_shift(&ce->mult, &ce->shift, NSEC_PER_SEC,
+ freq, minsec);
+}
+
#ifdef CONFIG_GENERIC_CLOCKEVENTS
extern void clockevents_notify(unsigned long reason, void *arg);
#else
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 83d2fbd..279c547 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -151,6 +151,7 @@ extern u64 timecounter_cyc2time(struct timecounter *tc,
* subtraction of non 64 bit counters
* @mult: cycle to nanosecond multiplier
* @shift: cycle to nanosecond divisor (power of two)
+ * @max_idle_ns: max idle time permitted by the clocksource (nsecs)
* @flags: flags describing special properties
* @vread: vsyscall based read
* @resume: resume function for the clocksource, if necessary
@@ -168,6 +169,7 @@ struct clocksource {
cycle_t mask;
u32 mult;
u32 shift;
+ u64 max_idle_ns;
unsigned long flags;
cycle_t (*vread)(void);
void (*resume)(void);
@@ -279,6 +281,16 @@ extern void clocksource_resume(void);
extern struct clocksource * __init __weak clocksource_default_clock(void);
extern void clocksource_mark_unstable(struct clocksource *cs);

+extern void
+clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);
+
+static inline void
+clocksource_calc_mult_shift(struct clocksource *cs, u32 freq, u32 minsec)
+{
+ return clocks_calc_mult_shift(&cs->mult, &cs->shift, freq,
+ NSEC_PER_SEC, minsec);
+}
+
#ifdef CONFIG_GENERIC_TIME_VSYSCALL
extern void update_vsyscall(struct timespec *ts, struct clocksource *c);
extern void update_vsyscall_tz(void);
diff --git a/include/linux/tick.h b/include/linux/tick.h
index 0482229..d2ae79e 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -43,6 +43,7 @@ enum tick_nohz_mode {
* @idle_exittime: Time when the idle state was left
* @idle_sleeptime: Sum of the time slept in idle with sched tick stopped
* @sleep_length: Duration of the current idle sleep
+ * @do_timer_lst: CPU was the last one doing do_timer before going idle
*/
struct tick_sched {
struct hrtimer sched_timer;
@@ -64,6 +65,7 @@ struct tick_sched {
unsigned long last_jiffies;
unsigned long next_jiffies;
ktime_t idle_expires;
+ int do_timer_last;
};

extern void __init tick_init(void);
@@ -98,6 +100,9 @@ extern int tick_check_oneshot_change(int allow_nohz);
extern struct tick_sched *tick_get_tick_sched(int cpu);
extern void tick_check_idle(int cpu);
extern int tick_oneshot_mode_active(void);
+# ifndef arch_needs_cpu
+# define arch_needs_cpu(cpu) (0)
+# endif
# else
static inline void tick_clock_notify(void) { }
static inline int tick_check_oneshot_change(int allow_nohz) { return 0; }
diff --git a/include/linux/time.h b/include/linux/time.h
index fe04e5e..6e026e4 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -148,6 +148,7 @@ extern void monotonic_to_bootbased(struct timespec *ts);

extern struct timespec timespec_trunc(struct timespec t, unsigned gran);
extern int timekeeping_valid_for_hres(void);
+extern u64 timekeeping_max_deferment(void);
extern void update_wall_time(void);
extern void update_xtime_cache(u64 nsec);
extern void timekeeping_leap_insert(int leapsecond);
diff --git a/include/linux/timex.h b/include/linux/timex.h
index e6967d1..0c0ef7d 100644
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -261,11 +261,7 @@ static inline int ntp_synced(void)

#define NTP_SCALE_SHIFT 32

-#ifdef CONFIG_NO_HZ
-#define NTP_INTERVAL_FREQ (2)
-#else
#define NTP_INTERVAL_FREQ (HZ)
-#endif
#define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ)

/* Returns how long ticks are at present, in ns / 2^NTP_SCALE_SHIFT. */
diff --git a/init/calibrate.c b/init/calibrate.c
index a379c90..6eb48e5 100644
--- a/init/calibrate.c
+++ b/init/calibrate.c
@@ -123,23 +123,26 @@ void __cpuinit calibrate_delay(void)
{
unsigned long ticks, loopbit;
int lps_precision = LPS_PREC;
+ static bool printed;

if (preset_lpj) {
loops_per_jiffy = preset_lpj;
- printk(KERN_INFO
- "Calibrating delay loop (skipped) preset value.. ");
- } else if ((smp_processor_id() == 0) && lpj_fine) {
+ if (!printed)
+ pr_info("Calibrating delay loop (skipped) "
+ "preset value.. ");
+ } else if ((!printed) && lpj_fine) {
loops_per_jiffy = lpj_fine;
- printk(KERN_INFO
- "Calibrating delay loop (skipped), "
+ pr_info("Calibrating delay loop (skipped), "
"value calculated using timer frequency.. ");
} else if ((loops_per_jiffy = calibrate_delay_direct()) != 0) {
- printk(KERN_INFO
- "Calibrating delay using timer specific routine.. ");
+ if (!printed)
+ pr_info("Calibrating delay using timer "
+ "specific routine.. ");
} else {
loops_per_jiffy = (1<<12);

- printk(KERN_INFO "Calibrating delay loop... ");
+ if (!printed)
+ pr_info("Calibrating delay loop... ");
while ((loops_per_jiffy <<= 1) != 0) {
/* wait for "start of" clock tick */
ticks = jiffies;
@@ -170,7 +173,10 @@ void __cpuinit calibrate_delay(void)
loops_per_jiffy &= ~loopbit;
}
}
- printk(KERN_CONT "%lu.%02lu BogoMIPS (lpj=%lu)\n",
+ if (!printed)
+ pr_cont("%lu.%02lu BogoMIPS (lpj=%lu)\n",
loops_per_jiffy/(500000/HZ),
(loops_per_jiffy/(5000/HZ)) % 100, loops_per_jiffy);
+
+ printed = true;
}
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 6ba0f1e..7c4e271 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -392,10 +392,9 @@ int disable_nonboot_cpus(void)
if (cpu == first_cpu)
continue;
error = _cpu_down(cpu, 1);
- if (!error) {
+ if (!error)
cpumask_set_cpu(cpu, frozen_cpus);
- printk("CPU%d is down\n", cpu);
- } else {
+ else {
printk(KERN_ERR "Error taking CPU%d down: %d\n",
cpu, error);
break;
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 6d70204..c215b74 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1240,7 +1240,8 @@ hrtimer_interrupt_hanging(struct clock_event_device *dev,
force_clock_reprogram = 1;
dev->min_delta_ns = (unsigned long)try_time.tv64 * 3;
printk(KERN_WARNING "hrtimer: interrupt too slow, "
- "forcing clock min delta to %lu ns\n", dev->min_delta_ns);
+ "forcing clock min delta to %llu ns\n",
+ (unsigned long long) dev->min_delta_ns);
}
/*
* High resolution timer interrupt
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 5c9dc22..438ff45 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -384,7 +384,8 @@ int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)

/*
* Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
- * This is called from sys_timer_create with the new timer already locked.
+ * This is called from sys_timer_create() and do_cpu_nanosleep() with the
+ * new timer already all-zeros initialized.
*/
int posix_cpu_timer_create(struct k_itimer *new_timer)
{
@@ -396,8 +397,6 @@ int posix_cpu_timer_create(struct k_itimer *new_timer)
return -EINVAL;

INIT_LIST_HEAD(&new_timer->it.cpu.entry);
- new_timer->it.cpu.incr.sched = 0;
- new_timer->it.cpu.expires.sched = 0;

read_lock(&tasklist_lock);
if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
diff --git a/kernel/time.c b/kernel/time.c
index 2e2e469..2ef4fe2 100644
--- a/kernel/time.c
+++ b/kernel/time.c
@@ -136,7 +136,6 @@ static inline void warp_clock(void)
write_seqlock_irq(&xtime_lock);
wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60;
xtime.tv_sec += sys_tz.tz_minuteswest * 60;
- update_xtime_cache(0);
write_sequnlock_irq(&xtime_lock);
clock_was_set();
}
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 620b58a..20a8920 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -20,6 +20,8 @@
#include <linux/sysdev.h>
#include <linux/tick.h>

+#include "tick-internal.h"
+
/* The registered clock event devices */
static LIST_HEAD(clockevent_devices);
static LIST_HEAD(clockevents_released);
@@ -37,10 +39,9 @@ static DEFINE_SPINLOCK(clockevents_lock);
*
* Math helper, returns latch value converted to nanoseconds (bound checked)
*/
-unsigned long clockevent_delta2ns(unsigned long latch,
- struct clock_event_device *evt)
+u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt)
{
- u64 clc = ((u64) latch << evt->shift);
+ u64 clc = (u64) latch << evt->shift;

if (unlikely(!evt->mult)) {
evt->mult = 1;
@@ -50,10 +51,10 @@ unsigned long clockevent_delta2ns(unsigned long latch,
do_div(clc, evt->mult);
if (clc < 1000)
clc = 1000;
- if (clc > LONG_MAX)
- clc = LONG_MAX;
+ if (clc > KTIME_MAX)
+ clc = KTIME_MAX;

- return (unsigned long) clc;
+ return clc;
}
EXPORT_SYMBOL_GPL(clockevent_delta2ns);

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 5e18c6a..72a2dcb 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -107,6 +107,59 @@ u64 timecounter_cyc2time(struct timecounter *tc,
}
EXPORT_SYMBOL(timecounter_cyc2time);

+/**
+ * clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks
+ * @mult: pointer to mult variable
+ * @shift: pointer to shift variable
+ * @from: frequency to convert from
+ * @to: frequency to convert to
+ * @minsec: guaranteed runtime conversion range in seconds
+ *
+ * The function evaluates the shift/mult pair for the scaled math
+ * operations of clocksources and clockevents.
+ *
+ * @to and @from are frequency values in HZ. For clock sources @to is
+ * NSEC_PER_SEC == 1GHz and @from is the counter frequency. For clock
+ * event @to is the counter frequency and @from is NSEC_PER_SEC.
+ *
+ * The @minsec conversion range argument controls the time frame in
+ * seconds which must be covered by the runtime conversion with the
+ * calculated mult and shift factors. This guarantees that no 64bit
+ * overflow happens when the input value of the conversion is
+ * multiplied with the calculated mult factor. Larger ranges may
+ * reduce the conversion accuracy by chosing smaller mult and shift
+ * factors.
+ */
+void
+clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec)
+{
+ u64 tmp;
+ u32 sft, sftacc= 32;
+
+ /*
+ * Calculate the shift factor which is limiting the conversion
+ * range:
+ */
+ tmp = ((u64)minsec * from) >> 32;
+ while (tmp) {
+ tmp >>=1;
+ sftacc--;
+ }
+
+ /*
+ * Find the conversion shift/mult pair which has the best
+ * accuracy and fits the maxsec conversion range:
+ */
+ for (sft = 32; sft > 0; sft--) {
+ tmp = (u64) to << sft;
+ do_div(tmp, from);
+ if ((tmp >> sftacc) == 0)
+ break;
+ }
+ *mult = tmp;
+ *shift = sft;
+}
+
/*[Clocksource internal variables]---------
* curr_clocksource:
* currently selected clocksource.
@@ -413,6 +466,47 @@ void clocksource_touch_watchdog(void)
clocksource_resume_watchdog();
}

+/**
+ * clocksource_max_deferment - Returns max time the clocksource can be deferred
+ * @cs: Pointer to clocksource
+ *
+ */
+static u64 clocksource_max_deferment(struct clocksource *cs)
+{
+ u64 max_nsecs, max_cycles;
+
+ /*
+ * Calculate the maximum number of cycles that we can pass to the
+ * cyc2ns function without overflowing a 64-bit signed result. The
+ * maximum number of cycles is equal to ULLONG_MAX/cs->mult which
+ * is equivalent to the below.
+ * max_cycles < (2^63)/cs->mult
+ * max_cycles < 2^(log2((2^63)/cs->mult))
+ * max_cycles < 2^(log2(2^63) - log2(cs->mult))
+ * max_cycles < 2^(63 - log2(cs->mult))
+ * max_cycles < 1 << (63 - log2(cs->mult))
+ * Please note that we add 1 to the result of the log2 to account for
+ * any rounding errors, ensure the above inequality is satisfied and
+ * no overflow will occur.
+ */
+ max_cycles = 1ULL << (63 - (ilog2(cs->mult) + 1));
+
+ /*
+ * The actual maximum number of cycles we can defer the clocksource is
+ * determined by the minimum of max_cycles and cs->mask.
+ */
+ max_cycles = min_t(u64, max_cycles, (u64) cs->mask);
+ max_nsecs = clocksource_cyc2ns(max_cycles, cs->mult, cs->shift);
+
+ /*
+ * To ensure that the clocksource does not wrap whilst we are idle,
+ * limit the time the clocksource can be deferred by 12.5%. Please
+ * note a margin of 12.5% is used because this can be computed with
+ * a shift, versus say 10% which would require division.
+ */
+ return max_nsecs - (max_nsecs >> 5);
+}
+
#ifdef CONFIG_GENERIC_TIME

/**
@@ -511,6 +605,9 @@ static void clocksource_enqueue(struct clocksource *cs)
*/
int clocksource_register(struct clocksource *cs)
{
+ /* calculate max idle time permitted for this clocksource */
+ cs->max_idle_ns = clocksource_max_deferment(cs);
+
mutex_lock(&clocksource_mutex);
clocksource_enqueue(cs);
clocksource_select();
diff --git a/kernel/time/tick-oneshot.c b/kernel/time/tick-oneshot.c
index a96c0e2..0a8a213 100644
--- a/kernel/time/tick-oneshot.c
+++ b/kernel/time/tick-oneshot.c
@@ -50,9 +50,9 @@ int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires,
dev->min_delta_ns += dev->min_delta_ns >> 1;

printk(KERN_WARNING
- "CE: %s increasing min_delta_ns to %lu nsec\n",
+ "CE: %s increasing min_delta_ns to %llu nsec\n",
dev->name ? dev->name : "?",
- dev->min_delta_ns << 1);
+ (unsigned long long) dev->min_delta_ns << 1);

i = 0;
}
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index e0f59a2..df133bc 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -134,18 +134,13 @@ __setup("nohz=", setup_tick_nohz);
* value. We do this unconditionally on any cpu, as we don't know whether the
* cpu, which has the update task assigned is in a long sleep.
*/
-static void tick_nohz_update_jiffies(void)
+static void tick_nohz_update_jiffies(ktime_t now)
{
int cpu = smp_processor_id();
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
unsigned long flags;
- ktime_t now;
-
- if (!ts->tick_stopped)
- return;

cpumask_clear_cpu(cpu, nohz_cpu_mask);
- now = ktime_get();
ts->idle_waketime = now;

local_irq_save(flags);
@@ -155,20 +150,17 @@ static void tick_nohz_update_jiffies(void)
touch_softlockup_watchdog();
}

-static void tick_nohz_stop_idle(int cpu)
+static void tick_nohz_stop_idle(int cpu, ktime_t now)
{
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
+ ktime_t delta;

- if (ts->idle_active) {
- ktime_t now, delta;
- now = ktime_get();
- delta = ktime_sub(now, ts->idle_entrytime);
- ts->idle_lastupdate = now;
- ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
- ts->idle_active = 0;
+ delta = ktime_sub(now, ts->idle_entrytime);
+ ts->idle_lastupdate = now;
+ ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
+ ts->idle_active = 0;

- sched_clock_idle_wakeup_event(0);
- }
+ sched_clock_idle_wakeup_event(0);
}

static ktime_t tick_nohz_start_idle(struct tick_sched *ts)
@@ -216,6 +208,7 @@ void tick_nohz_stop_sched_tick(int inidle)
struct tick_sched *ts;
ktime_t last_update, expires, now;
struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
+ u64 time_delta;
int cpu;

local_irq_save(flags);
@@ -258,7 +251,7 @@ void tick_nohz_stop_sched_tick(int inidle)

if (ratelimit < 10) {
printk(KERN_ERR "NOHZ: local_softirq_pending %02x\n",
- local_softirq_pending());
+ (unsigned int) local_softirq_pending());
ratelimit++;
}
goto end;
@@ -270,14 +263,18 @@ void tick_nohz_stop_sched_tick(int inidle)
seq = read_seqbegin(&xtime_lock);
last_update = last_jiffies_update;
last_jiffies = jiffies;
+ time_delta = timekeeping_max_deferment();
} while (read_seqretry(&xtime_lock, seq));

- /* Get the next timer wheel timer */
- next_jiffies = get_next_timer_interrupt(last_jiffies);
- delta_jiffies = next_jiffies - last_jiffies;
-
- if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu))
+ if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu) ||
+ arch_needs_cpu(cpu)) {
+ next_jiffies = last_jiffies + 1;
delta_jiffies = 1;
+ } else {
+ /* Get the next timer wheel timer */
+ next_jiffies = get_next_timer_interrupt(last_jiffies);
+ delta_jiffies = next_jiffies - last_jiffies;
+ }
/*
* Do not stop the tick, if we are only one off
* or if the cpu is required for rcu
@@ -289,22 +286,51 @@ void tick_nohz_stop_sched_tick(int inidle)
if ((long)delta_jiffies >= 1) {

/*
- * calculate the expiry time for the next timer wheel
- * timer
- */
- expires = ktime_add_ns(last_update, tick_period.tv64 *
- delta_jiffies);
-
- /*
* If this cpu is the one which updates jiffies, then
* give up the assignment and let it be taken by the
* cpu which runs the tick timer next, which might be
* this cpu as well. If we don't drop this here the
* jiffies might be stale and do_timer() never
- * invoked.
+ * invoked. Keep track of the fact that it was the one
+ * which had the do_timer() duty last. If this cpu is
+ * the one which had the do_timer() duty last, we
+ * limit the sleep time to the timekeeping
+ * max_deferement value which we retrieved
+ * above. Otherwise we can sleep as long as we want.
*/
- if (cpu == tick_do_timer_cpu)
+ if (cpu == tick_do_timer_cpu) {
tick_do_timer_cpu = TICK_DO_TIMER_NONE;
+ ts->do_timer_last = 1;
+ } else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) {
+ time_delta = KTIME_MAX;
+ ts->do_timer_last = 0;
+ } else if (!ts->do_timer_last) {
+ time_delta = KTIME_MAX;
+ }
+
+ /*
+ * calculate the expiry time for the next timer wheel
+ * timer. delta_jiffies >= NEXT_TIMER_MAX_DELTA signals
+ * that there is no timer pending or at least extremely
+ * far into the future (12 days for HZ=1000). In this
+ * case we set the expiry to the end of time.
+ */
+ if (likely(delta_jiffies < NEXT_TIMER_MAX_DELTA)) {
+ /*
+ * Calculate the time delta for the next timer event.
+ * If the time delta exceeds the maximum time delta
+ * permitted by the current clocksource then adjust
+ * the time delta accordingly to ensure the
+ * clocksource does not wrap.
+ */
+ time_delta = min_t(u64, time_delta,
+ tick_period.tv64 * delta_jiffies);
+ }
+
+ if (time_delta < KTIME_MAX)
+ expires = ktime_add_ns(last_update, time_delta);
+ else
+ expires.tv64 = KTIME_MAX;

if (delta_jiffies > 1)
cpumask_set_cpu(cpu, nohz_cpu_mask);
@@ -337,22 +363,19 @@ void tick_nohz_stop_sched_tick(int inidle)

ts->idle_sleeps++;

+ /* Mark expires */
+ ts->idle_expires = expires;
+
/*
- * delta_jiffies >= NEXT_TIMER_MAX_DELTA signals that
- * there is no timer pending or at least extremly far
- * into the future (12 days for HZ=1000). In this case
- * we simply stop the tick timer:
+ * If the expiration time == KTIME_MAX, then
+ * in this case we simply stop the tick timer.
*/
- if (unlikely(delta_jiffies >= NEXT_TIMER_MAX_DELTA)) {
- ts->idle_expires.tv64 = KTIME_MAX;
+ if (unlikely(expires.tv64 == KTIME_MAX)) {
if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
hrtimer_cancel(&ts->sched_timer);
goto out;
}

- /* Mark expiries */
- ts->idle_expires = expires;
-
if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
hrtimer_start(&ts->sched_timer, expires,
HRTIMER_MODE_ABS_PINNED);
@@ -431,7 +454,11 @@ void tick_nohz_restart_sched_tick(void)
ktime_t now;

local_irq_disable();
- tick_nohz_stop_idle(cpu);
+ if (ts->idle_active || (ts->inidle && ts->tick_stopped))
+ now = ktime_get();
+
+ if (ts->idle_active)
+ tick_nohz_stop_idle(cpu, now);

if (!ts->inidle || !ts->tick_stopped) {
ts->inidle = 0;
@@ -445,7 +472,6 @@ void tick_nohz_restart_sched_tick(void)

/* Update jiffies first */
select_nohz_load_balancer(0);
- now = ktime_get();
tick_do_update_jiffies64(now);
cpumask_clear_cpu(cpu, nohz_cpu_mask);

@@ -579,22 +605,18 @@ static void tick_nohz_switch_to_nohz(void)
* timer and do not touch the other magic bits which need to be done
* when idle is left.
*/
-static void tick_nohz_kick_tick(int cpu)
+static void tick_nohz_kick_tick(int cpu, ktime_t now)
{
#if 0
/* Switch back to 2.6.27 behaviour */

struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
- ktime_t delta, now;
-
- if (!ts->tick_stopped)
- return;
+ ktime_t delta;

/*
* Do not touch the tick device, when the next expiry is either
* already reached or less/equal than the tick period.
*/
- now = ktime_get();
delta = ktime_sub(hrtimer_get_expires(&ts->sched_timer), now);
if (delta.tv64 <= tick_period.tv64)
return;
@@ -603,9 +625,26 @@ static void tick_nohz_kick_tick(int cpu)
#endif
}

+static inline void tick_check_nohz(int cpu)
+{
+ struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
+ ktime_t now;
+
+ if (!ts->idle_active && !ts->tick_stopped)
+ return;
+ now = ktime_get();
+ if (ts->idle_active)
+ tick_nohz_stop_idle(cpu, now);
+ if (ts->tick_stopped) {
+ tick_nohz_update_jiffies(now);
+ tick_nohz_kick_tick(cpu, now);
+ }
+}
+
#else

static inline void tick_nohz_switch_to_nohz(void) { }
+static inline void tick_check_nohz(int cpu) { }

#endif /* NO_HZ */

@@ -615,11 +654,7 @@ static inline void tick_nohz_switch_to_nohz(void) { }
void tick_check_idle(int cpu)
{
tick_check_oneshot_broadcast(cpu);
-#ifdef CONFIG_NO_HZ
- tick_nohz_stop_idle(cpu);
- tick_nohz_update_jiffies();
- tick_nohz_kick_tick(cpu);
-#endif
+ tick_check_nohz(cpu);
}

/*
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index fb0f46f..5d4d423 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -164,13 +164,6 @@ struct timespec raw_time;
/* flag for if timekeeping is suspended */
int __read_mostly timekeeping_suspended;

-static struct timespec xtime_cache __attribute__ ((aligned (16)));
-void update_xtime_cache(u64 nsec)
-{
- xtime_cache = xtime;
- timespec_add_ns(&xtime_cache, nsec);
-}
-
/* must hold xtime_lock */
void timekeeping_leap_insert(int leapsecond)
{
@@ -331,8 +324,6 @@ int do_settimeofday(struct timespec *tv)

xtime = *tv;

- update_xtime_cache(0);
-
timekeeper.ntp_error = 0;
ntp_clear();

@@ -487,6 +478,17 @@ int timekeeping_valid_for_hres(void)
}

/**
+ * timekeeping_max_deferment - Returns max time the clocksource can be deferred
+ *
+ * Caller must observe xtime_lock via read_seqbegin/read_seqretry to
+ * ensure that the clocksource does not change!
+ */
+u64 timekeeping_max_deferment(void)
+{
+ return timekeeper.clock->max_idle_ns;
+}
+
+/**
* read_persistent_clock - Return time from the persistent clock.
*
* Weak dummy function for arches that do not yet support it.
@@ -547,7 +549,6 @@ void __init timekeeping_init(void)
}
set_normalized_timespec(&wall_to_monotonic,
-boot.tv_sec, -boot.tv_nsec);
- update_xtime_cache(0);
total_sleep_time.tv_sec = 0;
total_sleep_time.tv_nsec = 0;
write_sequnlock_irqrestore(&xtime_lock, flags);
@@ -581,7 +582,6 @@ static int timekeeping_resume(struct sys_device *dev)
wall_to_monotonic = timespec_sub(wall_to_monotonic, ts);
total_sleep_time = timespec_add_safe(total_sleep_time, ts);
}
- update_xtime_cache(0);
/* re-base the last cycle value */
timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
timekeeper.ntp_error = 0;
@@ -722,6 +722,49 @@ static void timekeeping_adjust(s64 offset)
}

/**
+ * logarithmic_accumulation - shifted accumulation of cycles
+ *
+ * This functions accumulates a shifted interval of cycles into
+ * into a shifted interval nanoseconds. Allows for O(log) accumulation
+ * loop.
+ *
+ * Returns the unconsumed cycles.
+ */
+static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
+{
+ u64 nsecps = (u64)NSEC_PER_SEC << timekeeper.shift;
+
+ /* If the offset is smaller then a shifted interval, do nothing */
+ if (offset < timekeeper.cycle_interval<<shift)
+ return offset;
+
+ /* Accumulate one shifted interval */
+ offset -= timekeeper.cycle_interval << shift;
+ timekeeper.clock->cycle_last += timekeeper.cycle_interval << shift;
+
+ timekeeper.xtime_nsec += timekeeper.xtime_interval << shift;
+ while (timekeeper.xtime_nsec >= nsecps) {
+ timekeeper.xtime_nsec -= nsecps;
+ xtime.tv_sec++;
+ second_overflow();
+ }
+
+ /* Accumulate into raw time */
+ raw_time.tv_nsec += timekeeper.raw_interval << shift;;
+ while (raw_time.tv_nsec >= NSEC_PER_SEC) {
+ raw_time.tv_nsec -= NSEC_PER_SEC;
+ raw_time.tv_sec++;
+ }
+
+ /* Accumulate error between NTP and clock interval */
+ timekeeper.ntp_error += tick_length << shift;
+ timekeeper.ntp_error -= timekeeper.xtime_interval <<
+ (timekeeper.ntp_error_shift + shift);
+
+ return offset;
+}
+
+/**
* update_wall_time - Uses the current clocksource to increment the wall time
*
* Called from the timer interrupt, must hold a write on xtime_lock.
@@ -730,7 +773,7 @@ void update_wall_time(void)
{
struct clocksource *clock;
cycle_t offset;
- u64 nsecs;
+ int shift = 0, maxshift;

/* Make sure we're fully resumed: */
if (unlikely(timekeeping_suspended))
@@ -744,33 +787,22 @@ void update_wall_time(void)
#endif
timekeeper.xtime_nsec = (s64)xtime.tv_nsec << timekeeper.shift;

- /* normally this loop will run just once, however in the
- * case of lost or late ticks, it will accumulate correctly.
+ /*
+ * With NO_HZ we may have to accumulate many cycle_intervals
+ * (think "ticks") worth of time at once. To do this efficiently,
+ * we calculate the largest doubling multiple of cycle_intervals
+ * that is smaller then the offset. We then accumulate that
+ * chunk in one go, and then try to consume the next smaller
+ * doubled multiple.
*/
+ shift = ilog2(offset) - ilog2(timekeeper.cycle_interval);
+ shift = max(0, shift);
+ /* Bound shift to one less then what overflows tick_length */
+ maxshift = (8*sizeof(tick_length) - (ilog2(tick_length)+1)) - 1;
+ shift = min(shift, maxshift);
while (offset >= timekeeper.cycle_interval) {
- u64 nsecps = (u64)NSEC_PER_SEC << timekeeper.shift;
-
- /* accumulate one interval */
- offset -= timekeeper.cycle_interval;
- clock->cycle_last += timekeeper.cycle_interval;
-
- timekeeper.xtime_nsec += timekeeper.xtime_interval;
- if (timekeeper.xtime_nsec >= nsecps) {
- timekeeper.xtime_nsec -= nsecps;
- xtime.tv_sec++;
- second_overflow();
- }
-
- raw_time.tv_nsec += timekeeper.raw_interval;
- if (raw_time.tv_nsec >= NSEC_PER_SEC) {
- raw_time.tv_nsec -= NSEC_PER_SEC;
- raw_time.tv_sec++;
- }
-
- /* accumulate error between NTP and clock interval */
- timekeeper.ntp_error += tick_length;
- timekeeper.ntp_error -= timekeeper.xtime_interval <<
- timekeeper.ntp_error_shift;
+ offset = logarithmic_accumulation(offset, shift);
+ shift--;
}

/* correct the clock when NTP error is too big */
@@ -806,9 +838,6 @@ void update_wall_time(void)
timekeeper.ntp_error += timekeeper.xtime_nsec <<
timekeeper.ntp_error_shift;

- nsecs = clocksource_cyc2ns(offset, timekeeper.mult, timekeeper.shift);
- update_xtime_cache(nsecs);
-
/* check to see if there is a new clocksource to use */
update_vsyscall(&xtime, timekeeper.clock);
}
@@ -845,13 +874,13 @@ void monotonic_to_bootbased(struct timespec *ts)

unsigned long get_seconds(void)
{
- return xtime_cache.tv_sec;
+ return xtime.tv_sec;
}
EXPORT_SYMBOL(get_seconds);

struct timespec __current_kernel_time(void)
{
- return xtime_cache;
+ return xtime;
}

struct timespec current_kernel_time(void)
@@ -861,8 +890,7 @@ struct timespec current_kernel_time(void)

do {
seq = read_seqbegin(&xtime_lock);
-
- now = xtime_cache;
+ now = xtime;
} while (read_seqretry(&xtime_lock, seq));

return now;
@@ -876,8 +904,7 @@ struct timespec get_monotonic_coarse(void)

do {
seq = read_seqbegin(&xtime_lock);
-
- now = xtime_cache;
+ now = xtime;
mono = wall_to_monotonic;
} while (read_seqretry(&xtime_lock, seq));

diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c
index 1b5b7aa..665c76e 100644
--- a/kernel/time/timer_list.c
+++ b/kernel/time/timer_list.c
@@ -204,10 +204,12 @@ print_tickdevice(struct seq_file *m, struct tick_device *td, int cpu)
return;
}
SEQ_printf(m, "%s\n", dev->name);
- SEQ_printf(m, " max_delta_ns: %lu\n", dev->max_delta_ns);
- SEQ_printf(m, " min_delta_ns: %lu\n", dev->min_delta_ns);
- SEQ_printf(m, " mult: %lu\n", dev->mult);
- SEQ_printf(m, " shift: %d\n", dev->shift);
+ SEQ_printf(m, " max_delta_ns: %llu\n",
+ (unsigned long long) dev->max_delta_ns);
+ SEQ_printf(m, " min_delta_ns: %llu\n",
+ (unsigned long long) dev->min_delta_ns);
+ SEQ_printf(m, " mult: %u\n", dev->mult);
+ SEQ_printf(m, " shift: %u\n", dev->shift);
SEQ_printf(m, " mode: %d\n", dev->mode);
SEQ_printf(m, " next_event: %Ld nsecs\n",
(unsigned long long) ktime_to_ns(dev->next_event));

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